1. Field of the Invention
The invention lies in the field of the production of metallic powders and metallic powder-containing devices which are protected against corrosion.
2. Brief Description of the Prior Art
The extensive literature in the general field of the protection of metals against the degrading influence of the ambient atmosphere, includes many references describing the protection of fine metallic particles against oxidation by encapsulating them in polymers (e.g., U.S. Pat. Nos. 3,556,838; 3,228,881; 3,228,882; 3,526,533 and 3,300,329). Such protection is necessary because many metals in finely divided form are so reactive as to burst into flame spontaneously upon exposure to air. Many others, which are not so pyrophoric, nevertheless, degrade too rapidly for device use in the absence of some protective treatment. In protective methods heretofore used, long chain polymers are employed to form a physically thick barrier against the interaction of oxygen with the surface of the metallic particle. In such methods it has been shown (Journal of the Electrochemical Society, 117 (1970) p. 137) that the reduction of the amount of protective material surrounding each particle tends to reduce the effectiveness of this corrosion protection treatment. The necessity to use a relatively large polymer volume, relative to the volume of metal is disadvantageous in many device uses.